The long-term objective is to obtain a 300 kV field emission electron microscope (FETEM) that will enhance, complement, and increase repertoire of imaging abilities to include cryoelectron microscopy of thick samples, EELS, STEM, and EDS. Presently there is no comparable intermediate voltage microscope system that is available to researchers at Northwestern University (NU). Funds are requested to purchase a JEOL 3200FS FETEM system that has several analytical modules. We will use the 3200FS to: 1) perform correlative light and electron microscopy in conjunction with our confocal systems, 2) image and analyze the cellular uptake of unique probes and nanoparticles, and 3) capture tilt-series of thick frozen-hydrated and resin-embedded samples for tomography. The 3200FS system can image thick samples (400nm-1(m). This FETEM provides reliable imaging and spectral analysis using specimen holders that can accommodate a wide variety of specimen types. Adding the analytical functions of EDS, EELS, and STEM makes this system extremely powerful - capable of investigating and characterizing many biological systems that are impossible with our current TEM. [unreadable] [unreadable] Together, the eight major users listed in this proposal have over 20 currently funded NIH grants totaling more than $5M. Their research projects encompass a wide array of developmental, cell, and structural biology studies including: 1) estrogen-induced plasticity of brain synapses, 2) cellular uptake of oligonucleotide- modified nanostructures, 3) the structure, function, and organization of viral surface glycoproteins, 4) structural studies of DNA topoisomerases, and 5) peptide amphiphile self-assembly. These and many other projects will significantly benefit from the additional imaging and analytical features of the 3200FS - features that our present TEM lacks. Results obtained from these studies will have significant impact on public health research in areas such as revealing molecular/cellular targets for novel therapeutic strategies for multiple brain/behavior disorders; designing/testing innovative nanoscale technologies that significantly improve cancer prevention, diagnosis, and treatment; and understanding the process of viral entry into host cells. Based on staff experience and on demonstrations of two 300 kV FETEM units (from FEI and JEOL), we have determined that the JEOL 3200FS system best suits our needs. This equipment will be administered by BIF on the NU Evanston campus. BIF is a shared-use facility that supports over 470 Northwestern researchers. BIF is also available to neighboring academic and health care institutions, and outside individuals. [unreadable] [unreadable] [unreadable]